We measured the size and shape of the right ventricle (RV) and its inlet and infundibulum (outflow) portions in 30 patients with EA aged 16–64 yrs and 9 normal subjects from MR images acquired in long and short axis and oblique views. The RV was traced and reconstructed in 3D as a triangular mesh using the piecewise smooth subdivision surface method. To define the volumes of the inlet and infundibulum, points were traced at the muscular ring separating the two portions, focusing on the supraventricular crest and the parietal, septal, and moderator bands. Care was taken to confirm the locations of these anatomic landmarks in intersecting views. A plane was fit to the points and used to cut the RV into inlet and infundibulum. Wall motion was measured in 13 regions by the centersurface method along chords drawn orthogonal to a surface constructed midway between the end diastolic (ED) and end systolic (ES) surfaces. The lengths of chords in each region were averaged and then normalized by dividing by the square root of body surface area. Tricuspid tilt was defined as the angle between the mitral and tricuspid annular planes, and tricuspid descent was the systolic excursion of the annulus centroid. See Figure 1.

Despite underdevelopment of the inlet, patients with EA have relatively preserved function in this portion of the RV. Three dimensional surface reconstruction enables separate analysis of the inlet and infundibulum portions of the RV as well as detailed assessment of regional function and shape.